Unit 4: Cell Membrane Notes Plasma/Cell Membrane Border to cell, controls what enters and leaves the cell. Selectively Permeable – some things can pass through the cell membrane, others can not.

Fluid Mosaic Model This is the model used to describe the cell membrane. “Fluid” means the cell membrane is in a watery environment and capable of moving. “Mosaic” means made of many different parts.

Phospholipid Hydrophilic- Loves water-Phosphate Head Hydrophobic- Hates water-Lipid Tail Phosphate Head Lipid Tail

Transport Protein A protein that helps transport molecules too large to diffuse. (a)A protein channel (Bridge) (b)A carrier protein (Car)

Marker Protein Marker proteins are on the outside of the cell. They have carbohydrate chains attached to them. It allows other cells to identify it. All of your body’s cells have a marker on them so that the cells know they are all a part of your body.

Receptor Protein Just like it sounds, these proteins receive things like chemicals and signals from other cells.

Cholesterol Helps firm the cell membrane, So it’s not too fluid. It also makes certain sections of the membrane less permeable to small molecule. Keeps lipid tails untangled.

A diagram of the cell membrane with all its parts

Concentration Gradient How concentrated molecules are. Naturally moves from High to low.

Passive Transport-No Energy Diffusion Molecules move from high To low concentration. Facilitated Diffusion Molecules need the help Of a transport protein, but it Requires no energy.

Examples of Passive Transport Respiratory System Gas exchange between alveoli (air sacs in lungs) and capillaries (tiny blood vessels)

Digestive System Monomers (from food) travel from the villi in small intestine to blood vessels Examples of Passive Transport

Circulatory System Gases and material travel from blood to all kinds of cells in the body Examples of Passive Transport

Urinary System The kidneys filter out toxins from the blood Regulates water balance Examples of Passive Transport

Osmosis Diffusion of Water, through a selectively permeable membrane.

Active Transport-Energy Needed Endocytosis Bringing food into The cell. Exocytosis Getting wastes out Of the cell. Protein Pump Special type of transport protien That moves molecules AGAINST The concentration gradient. Requires Energy.

Examples of Active Transport Immune System White Blood Cells destroy invading pathogens

Examples of Active Transport Creating Concentration Gradients There is a lot of Potassium inside of the cell and a lot of Sodium outside of the cell to create a concentration gradient needed for sending electrical messages

Solutions Solute- what’s being dissolved (sugar, salt, etc.) Solvent- what’s doing the dissolving (water) Solution- the combination of solute and solvent.

Hypertonic Solution Which way will the water go? Water goes out the cell. How does it move? Osmosis

Hypotonic Solution Which way will the water go? Water enters the cell. How does it move? Osmosis

Isotonic Solution Which way will the water go? Water enters and leaves the cell at the same rate. How does it move? Osmosis

Solutions

NOTES: Cell Cycle Why do cells have to divide? DNA Overload – the Nucleus (boss of cell) can’t get the messages out to organelles fast enough. Nike company vs. mom and pop shop example Material Exchange– Food and waste are in volume and cannot enter or leave the cell fast enough

Surface Area and Volume Let’s do Math! 1x1x1 SA: Volume: SA to Volume Ratio: 6x6x6 SA: Volume: SA to volume Ratio: 10x10x10 SA: Volume: SA to Volume Ratio:

What are new cells used for? Growth and Repair

Forms of a chromosome NOTES: Cell Cycle There is more than one form of DNA!!! And they will all be found in a cell at some time.

NOTES: Forms of a Chromosome Chromatin Definition: Long stringy form of DNA. DNA will be in this shape while the cell is in Interphase or the “normal” phase.

NOTES: Forms of a Chromosome Chromosome (Sister Chromatids) Definition: Tightly condensed and coiled Chromatin. It looks kinda like an “X.” The center of the chromosome, where the 2 ½ s of the chromosome meet is called a centromere.

NOTES: Forms of a Chromosome Chromatid Definition: ½ a side of a chromosome.

Centrioles – Important Vocabulary NOTES: Cell Cycle ONLY FOUND IN ANIMAL CELLS! Have strings/fibers called spindles that will move chromosomes around in the cell.

Cell Plate – Important Vocabulary NOTES: Cell Cycle Cleavage Furrow – Cytokinesis in Animal Cells. Pinches inward Cytokinesis in Plant cells. Starts in the middle and grows out.

Cell Cycle Phases: INTERPHASE Normal Cell Nucleus not undergoing mitosis yet.

Cell Cycle Phases: PROPHASE The nuclear membrane disintegrates. The chromosomes are floating in the cytoplasm and are composed of two chromatids joined at the centromere. Centrioles have completed their migration to opposite poles.

Cell Cycle Phases: METAPHASE The chromosomes are lined up across the center. Spindle fibers develop and attach to the chromosomes at the centromere.

Cell Cycle Phases: ANAPHASE Chromatids are pulled apart and travel up the spindle fibers. The chromatids are now single stranded chromosomes. The cell membrane starts to pinch the cytoplasm.

Cell Cycle Phases: TELOPHASE Chromosomes uncoil and the nucleus begins to reform. Division of cytoplasm has begun

Cell Cycle Phases: CYTOKINESIS Mitosis and cell division are complete producing two new daughter cells. Normal nuclei are to be seen.

Phases of the Cell Cycle

Real Pictures of the Cell Cycle ANIMAL CELLS PLANT CELLS

Extras Pinocytosis- bringing water into the cell. Phagocytosis- bringing food into the cell. (think of your esophagus…) Homeostasis- maintaining a constant internal environment.